Your doctor may need to change the doses of your medications or monitor you carefully for side effects. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Tell your doctor if any of these symptoms are severe or do not go away: headache. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. Continue to take sildenafil even if you feel well.Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP. Viagra: This drug is used to treat ED. With ED, you’re unable to get or maintain an erection. Revatio: This drug is used to treat PAH. With PAH, the blood pressure in your lungs is too high. Your. Viagra (sildenafil) is approved to treat sexual dysfunction in men by the U.S. Food and Drug Administration (FDA), but it is sometimes prescribed to women off-label, which means without approval by the FDA. Viagra is an effective drug for treating male erectile dysfunction, but it targets sexual performance, not sexual arousal.